1. Field of the Invention
The invention relates to heating ventilating and air conditioning control based on real-time imaging of occupied spaces to determine load and more particularly to such control that uses, among other things, techniques for counting individuals and tracking their movement to determine conditioned-space occupancy rates.
2. Background
There are a number of techniques for controlling heating ventilating and air conditioning (HVAC). Most commonly, they are regulated based on temperature. But pure temperature-based regulation gives an incomplete picture of the load because human comfort also involves humidity and contaminant control, which may be regulated by dehumidification and ventilation components of a system, respectively. For example, carbon dioxide (CO2), moisture, or other contaminant levels may rise to unacceptable levels due to high occupancy, smoking, cooking, and other such activities. To address these issues, large-scale HVAC systems may employ contaminant sensors such as CO2 sensors and humidity sensors in the control of HVAC systems. However, the sensors used in such systems are expensive and often inaccurate or prone to failure. Also, placement of such sensors may be based on use and structure patterns in a space that are changed thereby reducing their effectiveness. For example, local occupancy patterns in a large space may be completely ignored by such control devices.
A control system for heating ventilating and air conditioning (HVAC) systems employs video cameras and image processing techniques to detect occupancy and use patterns in a conditioned space. The HVAC system is preferably capable of delivering local effect, such as through zone-control, spot-cooling, heating, or ventilating, exhaust, etc. By counting occupants by zone and/or controlled area, energy can be saved and comfort and safety maximized.
Examples of environments to which the invention is applicable include simple zone-controlled systems such as in residences and large buildings. In such cases, cameras may be mounted in each zone to permit a head-count of occupants in real time. The control system may make predictions based on the detected zone-occupancy outdoor temperature and humidity, current temperature and humidity, to control the supply of heating, ventilating, and cooling effect delivered to the occupied zone.
Another example of an application is a factory. Image processing systems may be trained to recognize, in real-time images, not only occupancy but activities as well. For example, the system could detect welding or painting activity, activities that have visible manifestations, and control the local exhaust rate accordingly. Spot coolers could be controlled to turn off even when the user takes a break. Yet another example is a high occupancy space such as a trade-show venue. Movement patterns in such environments are otherwise very difficult to detect.
The invention will be described in connection with certain preferred embodiments, with reference to the following illustrative figures so that it may be more fully understood. With reference to the figures, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.